1. Field of the Invention
The present invention relates to high refractive index and low birefringence organic/inorganic hybrid materials useful for optical applications.
2. Description of the Related Art
Many optical applications require high refractive index materials including filters, transmitters, reflectors, lenses, optical waveguides, sensors, devices, adhesives for optical components and device assembly, index matched materials for solid state laser, optical components. The organic/inorganic hybrid materials have been used to prepare high refractive index materials. For examples, Wilkes et al. (U.S. Pat. No. 5,109,080) have been reported that a refractive index ranged from 1.60-1.76 can be obtained from a solvent based polyarylether(sulfone) containing SiO2xe2x80x94TiO2xe2x80x94ZrO2. It is known that the aromatic moiety of polymer exhibits undesired birefringence properties for optical applications (Chem. and Eng. News p14-15, Dec. 20, 1999). The system also contained tetrahydrofuran and alcohol solvents. The tetrahydrofuran was used to dissolve polyarylether(sulfone) and the alcohol was used to obtain the metal oxide precursor solution. The solvents were also used (1) to carry out the reaction between organic component and inorganic component, and (2) to adjust the viscosity of the system for the ease of processing. However, the solvents create pollution problems during the processing. Zimmerman et al. (L. Zimmermann, M. Weibel, W. Caseri and U. W. Suter, J. Mater. Res., 8(7), 1993, p. 1742-48) prepared a gelatin-PbS system that has a refractive index range from 1.5 to 2.5. Kyprianidou-Leodidou et al (T. Kyprianidou-Leodidou , H-J. Althaus, Y. Wyser, D. Vetter, M. Bucher, W Caseri and U. W. Suter, J. Mater Res. 12(8), 1997, p. 2198-2206) synthesized high refractive index material from polyethyleneoxide-FeS (refractive index 2.5-2.8) and polyethyleneoxide-PbS (refractive index 3.9). However, gelatin and polyethyleneoxide are hydrophilic and absorb moisture easily, lack mechanical strength and dimensional stability. PbS is undesirable in the application due to its highly toxic nature of lead compound. Therefore, there is a need for an environmental friendly high refractive index, low birefringence and nontoxic organic/inorganic hybrid materials.
It is an object of the present application to provide high refractive index and low birefringence organic/inorganic hybrid materials that are prepared from solventless metal aliphatic acryl alkoxides. The metal aliphatic acryl alkoxides are synthesized first. Then, the metal aliphatic acryl alkoxides are hydrolyzed to form nanoparticle metal oxide dispersed acrylates. They can be free radical polymerized (via thermal or photo) into high refractive index, low birefringence, high mechanical strength and low moisture absorption metal oxide dispersed aliphatic polyacrylates.
It is a further object of the present invention to provide organic/inorganic hybrid materials that are solventless, nontoxic, high refractive index, low birefringence, high mechanical strength and low moisture absorption.
It is an additional object of the present invention to provide a method of making organic/inorganic materials of present invention.
A more complete understanding of these and other features and advantages of the present invention will become apparent from a careful consideration of the following detailed description of certain embodiments and the illustrations as shown in the following drawings.